Accessing a vector form a matrix

Hi, I am writing a solver scipt where I will have outputed 3 vectors called x1, x2, and x3. I then plan to turn these into a 3 x (some value tbd) vector, meaning x=[x1, x2, x3].

In the main script I need to plot x1, x2 and x3 independently, which brings me to my question. How do I call, for instance, the x1 vector from the 'x' matrix so I can plot it please?

[Dyuman Joshi]

Use indexing - https://in.mathworks.com/help/matlab/math/array-indexing.html

[Stephen23]

Indexing is a very basic (and powerful) feature of MATLAB:

https://www.mathworks.com/help/matlab/getting-started-with-matlab.html

Answer 1

[John D'Errico]

As an example, given vectors x1,x2,x3. I'll make some up.

x1 = randi(10,1,5)

x1 = 1x5

7 8 6 4 1

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x2 = randi(10,1,5)

x2 = 1x5

9 5 5 6 3

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x3 = randi(10,1,5)

x3 = 1x5

2 3 10 10 8

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Combine them into an array, here of size 3x5.

x = [x1;x2;x3]

x = 3x5

7 8 6 4 1 9 5 5 6 3 2 3 10 10 8

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You can access the original x1 as:

x(1,:)

ans = 1x5

7 8 6 4 1

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Answer 2

[Hassaan]

% Dummy data for vectors x1, x2, and x3
x1 = sin(linspace(0, 2*pi, 100));  % Example data for x1 (a sine wave)
x2 = cos(linspace(0, 2*pi, 100));  % Example data for x2 (a cosine wave)
x3 = linspace(0, 1, 100);          % Example data for x3 (a linear increase)

% Combine x1, x2, and x3 into a single matrix x
x = [x1; x2; x3]';

% Extract each vector from the matrix x
extracted_x1 = x(:, 1);  % This extracts the first column from matrix x, which is vector x1
extracted_x2 = x(:, 2);  % This extracts the second column, which is vector x2
extracted_x3 = x(:, 3);  % This extracts the third column, which is vector x3

% Plot each vector individually
% Plot for x1
figure;  % Open a new figure window for x1
plot(extracted_x1, 'b-', 'LineWidth', 2);  % Plot x1 with a blue line
title('Plot of x1');
xlabel('Index');
ylabel('Value');

% Plot for x2
figure;  % Open a new figure window for x2
plot(extracted_x2, 'r-', 'LineWidth', 2);  % Plot x2 with a red line
title('Plot of x2');
xlabel('Index');
ylabel('Value');

% Plot for x3
figure;  % Open a new figure window for x3
plot(extracted_x3, 'g-', 'LineWidth', 2);  % Plot x3 with a green line
title('Plot of x3');
xlabel('Index');
ylabel('Value');

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